A reactor is one of parts in a circuit that performs a step-up operation and a step-down operation of a voltage. For example, Patent Literature 1 discloses, as a reactor that is used for a converter mounted on a vehicle such as a hybrid electric vehicle, a reactor including a coil having a pair of coil elements arranged side by side, a magnetic core formed like a ring by a pair of inner cores (intermediate cores) where the coil elements are arranged respectively and a pair of outer cores (end cores) where the coil is not arranged, and a cylindrical bobbin and a frame-shaped bobbin which are provided between the coil and the magnetic core and enhance their insulation performance.
As described in Patent Literature 1, there is taken a mode in which the inner core is formed by a stacked steel plate obtained by stacking a thin sheet such as a silicon steel sheet or a stack obtained by alternately stacking a core piece formed by a powder magnetic core and a plate-shaped gap member made of ceramics or the like, and the outer core is formed by the core piece. The cylindrical bobbin is provided between the inner core formed by the stack and the coil element, and the frame-shaped bobbin is provided between an end surface of the coil element and an inner end surface disposed on the inner core side in the outer core (Patent Literature 1).
The reactor having the structure is assembled in the following manner.
(1) The core piece and the gap member are stacked to form the inner core.
(2) The cylindrical bobbin is disposed on an outer periphery of the inner core.
(3) Two inner cores including the cylindrical bobbin are fabricated and inserted into the coil elements, respectively.
(4) The core piece configuring the frame-shaped bobbin and the outer core is disposed to interpose the two inner cores which are disposed on the coil elements so that the two inner cores are arranged side by side, and the inner core and the outer core are properly bonded to each other.